Answer:
1) x - 4 is greater than or equal to 18
x is greater than or equal to 22
2) 12 + x is less then or equal to 17
x is less the or equal to 5
3) 23 is less than x + 16
7 is less than x
4) -6 + x is greater than or equal to -7
x is greater than or equal to -1